1. Field of the Invention
The present invention relates to a semiconductor device testing method and a semiconductor device manufacturing method. In particular, the present invention relates to a testing method by which a semiconductor device is screened for failure and a semiconductor device manufacturing method including a screening process.
2. Description of the Related Art
One of the main features of semiconductor devices is high reliability, which cannot be obtained in other electronic devices. The high reliability of the semiconductor devices can be achieved by screening for eliminating semiconductor devices having a high failure rate. An acceleration test has been generally executed to test semiconductor devices that have been screened for a short period of time. In the acceleration test, the operation of a mechanism is accelerated in an operational condition that is more strict than an ordinary operational condition, and the semiconductor devices are screened based on the effects of the accelerated operation of the mechanism.
The semiconductor device acceleration test checks for semiconductor devices having the potential to fail the test by applying thermal stress, electrical stress, and the like thereto and eliminates the semiconductor devices with potential for failure. The semiconductor devices with a potential to fail have various reasons for failure. Further, a wide variety of failure modes are observed when the semiconductor devices are checked. Thus, various acceleration tests are employed according to the failure modes.
Among the acceleration tests, burn-in testing, which has a purpose of detecting and eliminating a failed gate oxide film, is known as the most effective acceleration test. In the burn-in testing, a semiconductor device is placed in an atmosphere of 100° C. to 150° C., and an electric field, which is as large as or twice as large as an actually used electric field, is applied to the semiconductor device. In the burn-in testing, the semiconductor device is held for a predetermined period of time in s stand-by state or in a dynamic state. The time to failure of the gate oxide film is ordinarly proportional to the minus one power of an electric field applied thereto. Therefore, the burn-in testing can effectively accelerate the time to failure of the gate oxide film. As a result, the burn-in testing is effective as an acceleration test of the gate oxide film.
In contrast, a wiring step in a semiconductor device manufacturing process has many factors for causing failure. Wiring breakage caused by using copper as a wiring material is one of the factors for causing failure. A failure mode called stress migration is widely known by which wirings are broken in a high temperature cycle or when they are left in a high temperature environment. In stress migration, voids are created in the wirings by the stress applied to a wiring pattern by the difference of thermal expansion factors between the wirings and interlayer insulation films or by external heat. The voids grow and break the wirings. Since the time to failure of the stress migration has no relation to the electric field applied to semiconductor devices, it cannot be screened by the burn-in testing. Accordingly, the breaking failure of semiconductor devices cannot be eliminated before they are shipped, thereby the reliability of the semiconductor devices is decreased.